MoTeC Global Forum

Can someone please advise exactly what conditions are met to trigger this error please?

Thanks!

This error is a warning indicating that the injector is getting close to the maximum duty cycle. It usually comes on when injector duty cycle reaches about 93% so that there is a bit of margin between the error status and the injector being open continuosly. If you see this error it is an indication that you need to look at injector sizing and fuel delivery, you may need bigger injectors, increased fuel pressure and/or a better fuel pump.

RossB wrote:This error is a warning indicating that the injector is getting close to the maximum duty cycle. It usually comes on when injector duty cycle reaches about 93% so that there is a bit of margin between the error status and the injector being open continuosly. If you see this error it is an indication that you need to look at injector sizing and fuel delivery, you may need bigger injectors, increased fuel pressure and/or a better fuel pump.

I have this problem too once in a while. I have 4 1600cc primary injectors and 4 secondary 2200 cc injectors running on alchohol on a 4 cyl 4g63 motor running peak boost of 55 psi. I have ample injector according to math calculations, yet this seems to happen. Base fuel psi is set to 45 psi with 1 psi gain per 1 psi of boost. I have a Weldon mech pump rated at 1200 HP Alchohol. I dynoed 980 whp. I am not sure why this happens.

You probably have not taken the effects of the balance table on injector duty cycle. Remember that 0% in the table mean all fuel from your 1600cc injectors and 100% is all from the 2200cc injectors.

You would think that 50% in the table gives you the maximum volume of fuel from you system but this is incorrect
as the 1600CC injectors will reach full duty cycle before the 2200cc ones which will flag the duty cycle error.

The maximum flow rate from the system would be something like 63%

RossB wrote:This error is a warning indicating that the injector is getting close to the maximum duty cycle. It usually comes on when injector duty cycle reaches about 93% so that there is a bit of margin between the error status and the injector being open continuosly. If you see this error it is an indication that you need to look at injector sizing and fuel delivery, you may need bigger injectors, increased fuel pressure and/or a better fuel pump.

Thanks Ross,
I had a feeling that it might be something like that.
Still, I will have to consider bigger injectors for my application going forward...

Setting the balance table to give equal pulsewidth to high and low injectors will give you the maximum possible flow from the pair.

The following formula will give you the balance table number that accomplishes this

(1/((Secondary Flow Rate/Primary Flow Rate)+1))*100

Using the injectors listed above as the example:

Secondary Flow Rate of 2200 / Primary Flow Rate of 1600 = 1.375

1.375 + 1 = 2.375

1 / 2.375 = .42

.42 * 100 = 42 which is the value you should use in the balance table for equal pulsewidths.

This does not take into account the difference in dead time that may exist between the high and low injectors but it will get you very close to equal pulsewidth and will maximise the flow potential of the pair.